1. Field of the Invention
The invention relates to a high-speed printing device in which a recording carrier is fed to a printing station via a paper channel.
2. Description of the Related Art
Non-mechanical printers, such as for example laser printers, printers operating with LED combs, magnetic printers or printers operating with ink pressure are generally used as modern high-speed printing devices. These are generally known and have been applied successfully.
In printers operating according to the principle of electrophotography, a latent image is produced on a photoconductive drum with the aid of a light source which is controlled in a character-dependent manner, this image being inked in a developer station by applying toner and then transferred onto a recording carrier in a subsequent transfer station. The image, which is located loosely on the recording carrier and consists of toner, is then fixed with the aid of a fixing device.
The photoconductive drums, used as intermediate carriers, of electrophotographic printers, whether they are made of inorganic or organic material, have a sensitive surface which can be easily scratched. Metal particles, e.g. paper clips, which may be entrained with the recording carrier, can damage the surface of the photoconductive drum, which leads to a fault on the printed image which can no longer be corrected.
With non-mechanical printing devices which operate with ink pressure, whether using a head which is moved line by line or an ink comb, it is also possible that, due to the close spacing required between ink outlet nozzles and recording carrier, a particle which is entrained with the recording carrier can lead to faults in the writing operation or to damage to the ink head or ink comb.
In order to prevent the ingress of particles, it is therefore customary in high-speed printing devices of every kind to cover or encapsulate the paper feed.
However, high-speed printing devices are generally operated in conjunction with EDP (electronic data processing) systems and operated by the same operating personnel. For this reason, the printing devices must be designed in such a way that virtually interruption-free printing is ensured. Thus, after a paper stack is consumed, it must be possible to insert a new stack very quickly without a substantial interruption time. For this reason, it is necessary to design the printing device in an ergonomically optimum fashion; this applies in particular to the insertion and removal of the paper and to the maintenance of the overall system. For this reason, it must be possible to open the printing device wide with the purpose of inserting the recording carrier. Thus, there is a risk of particles such as paper clips or the like getting into the region of the recording carrier during insertion and becoming stuck there, for example, due to electrostatic forces.